In order to make recent mobile terminals conform to a bulk data transmission system, use of a plurality of antenna elements has been studied. Since 800 MHz, 1.5 GHz, 1.7 GHz, and 2.0 GHz bands are used even for a current cellular transmission method, development of an antenna capable of conforming to the multi-band has been expected. When a compact mobile terminal is equipped with a plurality of antenna elements, a high degree of isolation among antenna elements must be assured so as not to deteriorate coupling between the antenna elements. In particular, even when there are adopted measures to prevent deterioration of coupling among antenna elements, the measures will not make sense if antenna efficiency becomes worse when the mobile terminal is held by hand (in other words, when the mobile terminal is kept in hand). For these reasons, a low coupling technique that suppresses deterioration of antenna efficiency even in such a case has been sought.
Patent Document 1 discloses a technique for effecting low coupling of two antenna elements with a junction element, such as a filter, interposed therebetween. Non-Patent Document 1 discloses a technique for setting two concentrated constants on a two-element monopole antenna having one resonance frequency, thereby effecting low coupling at a maximum of two frequencies.